NEED HELP Physics Power Dissipation A Level

Why do we use the equation P=I^2xR to calculate the power lost? This is on the topic of minimising power loss in a transmission cable. The book says that voltage needs to be raised in order to lower the current to minimise power loss. But from the other formula of calculating power, ie P=V^2/R we can see that power is proportional to voltage.

Why do we have to lower current and not voltage to minimise power loss? Im so confused

Reply 1

lmaololoaml

you want a high power (minimal power loss). to achieve this you use a high voltage and low current. you need the current low to minimise heating the wire and hence increasing the resistance, etc.

you need the high voltage as P=IV

Reply 2

lmaololoaml

i think my teacher said to use P=I^2xR as it is easier to use when working out the power loss. a couple of students find it confusing what V to use if you used P=IV or P=V^2/R, whereas the current and R are straight forward enough to know what values to use